Nicholls, who has played 67 ODIs, can cover most of the top-order positions, which would be valuable if Williamson were unavailable for the start of the tournament.
The 31-year-old is currently with the team in England, where he opened the batting during the 2019 tournament, while Chapman returned home after the T20 series for the birth of his child.
Chapman has played only 10 ODIs after switching his allegiance from Hong Kong, though he compiled a couple of decent knocks against Pakistan in May. The 29-year-old has a superior record in T20 cricket and could be seen as a closing option in the absence of Michael Bracewell.
The spinning all-rounder’s Achilles injury created an opening for Rachin Ravindra, who picked an opportune time to record best bowling figures of 3-48 in the first ODI against England, likely earning inclusion alongside Sodhi and Mitchell Santner.
That would leave the final spot in the squad determined by the selection of a fifth fast bowler — or the decision of whether one is required in spin-friendly conditions in India.
With Trent Boult returning to the team alongside Tim Southee, Matt Henry and Lockie Ferguson, Milne and Kyle Jamieson seemed locked in a decisive duel.
Milne’s pace appealed as an enticing point of difference but the injury-prone quick was ruled out of the ODI series in England with an ill-timed, low-grade hamstring injury.
The 31-year-old will now be racing to prove his fitness before the provisional squad becomes final at the end of the month, ahead of the Black Caps’ opener against England on October 5.
Jamieson — having battled back from injuries of his own — hardly seized on Milne’s absence in the first match in England, returning 0-61 from seven overs during his first ODI in more than a year.
The temptation could be to gamble on neither Milne nor Jamieson and bolster the batting depth by including both Nicholls and Chapman, with the door also ajar for all-rounder Jimmy Neesham.
Possible Black Caps squad:
Kane Williamson (c), Devon Conway, Will Young, Tom Latham, Henry Nicholls, Daryl Mitchell, Glenn Phillips, Mark Chapman, Mitchell Santner, Rachin Ravindra, Ish Sodhi, Matt Henry, Tim Southee, Lockie Ferguson, Trent Boult.